I think when we think and talk about boundaries, codependency, and loving and nurturing ourselves, we have to be very careful. Actually, I think we have to be careful when we talk about helping others as well. I think it’s very easy to be confused with this, and that we often may think we are doing the right thing but may really be doing something unbalanced or selfish without realizing it, while following the best of human motives and current wisdom. I am absolutely thinking of myself as I write this. Over the years the best I've come to is that I can't know, and can be pulled the wrong way by my own "selfish" desires, even the desire to help, or the desire to act rightly; and that the only "right" way to act is to seek the guidance of the Holy Spirit in each case (knowing that I can sometimes even be mistaken when trying to do that, because I'm human).
I think any set of rules saying, "Always do this," is wrong. Even following the parable of the Good Samaritan can be "wrong", because some evil people prey upon that by pretending to be hurt and then killing or robbing those who stop to help. It takes discernment and guidance from the Spirit each time. ("Be ye therefore wise as serpents, and harmless as doves" Matthew 10:16) Or, for example, certain ways of helping can actually be saying to the person you are trying to help that you think he or she is incapable, unable, and needs you (or would fail or die or whatever); while other ways build up that person's ability and confidence, and imply that you are both co-travelers in life, each of whom may need help from time to time. (There's interesting psychological writing on triangulation, and especially on the victim, attacker, and rescuer triangle, where roles can easily change, and the one who was trying to rescue now either gets attacked or becomes abusive.)
All of the writing and wisdom about codependency, boundaries, tough love, and the like is very useful, especially if we didn't have good modeling of appropriate boundaries growing up. However, true, good, and right love and healing cross boundaries. Jesus crossed boundaries in his work all the time. He also had utmost respect for people's selves and autonomy and decisions; he often asked if they wanted to be well, and responded to people calling or coming to him. He did very different things for different people; he did not use a formula.
If we try to make a rule for ourselves, we can easily err, either on the side of being selfish, hiding behind the rule of boundaries; or by exhausting and depleting ourselves following a rule that says we always have to give. I am human, and limited by time, space, and my body. I, for example, can only be a mother, a friend, a wife, and even a doctor, to a limited number of people. I could not be a doctor to all the people of a city, or even a medium sized town. There might be a person who could be physically or psychologically or spiritually saved by my extending beyond my normal boundaries; there could be another who might only be "saved" by my insisting on his or her own ability and accountablity, and I might be "lost" in trying to give and give to such a person. I am not wise enough on my own to know the difference.
Again, the best example I have found for trying to maneuver through these pitfalls is that of Jesus. He would spend tremendous time and energy healing people and teaching crowds. Then he would withdraw into places in nature to be alone and pray to God (even when people were still begging for his time and attention). He said he only did and said what his Father told him to do and say. He looked to the spirit of the law, not to its literal interpretation. He looked at people's hearts and spirits.
Love and healing come from somewhere deeper and higher than our laws and rules do. Laws and rules attempt to codify things and make them safe; in the process things can become rote and bureaucratic, with overtones of slavery and unwitting evil. There is a glorious freedom and health that comes from wisely breaking those boundaries when led by the Holy Spirit. Breaking them when led by our own selfish desires leads to misery and pain. It takes experience, prayer, earnest seeking, discernment, wisdom, learning, and listening to the Holy Spirit to know the difference. (And I don't personally pretend to be more than partway on this journey.)
Love and healing are built into us. We naturally turn to our parents and then to others with love; our bodies naturally heal. There is a higher and deeper level of both; we recognize it at a remarkable level in some people, for example with Mother Teresa. Lawrence LeShan wrote an interesting book called "The Medium, the Mystic, and the Physicist", and then "Alternate Realities", talking about different ways of looking at and experiencing the world. For example, in the western scientific method, we've achieved amazing technological and medical discoveries. He says that in the world view of a mystic, it's like each of us is a wave on a vast ocean, and the power of the whole ocean can be focused on an individual wave, allowing miraculous results (such as healing that would be beyond the ability of the body to normally achieve). There is no way for such a thing to happen in the scientific worldview.
Our western society systematically embraces the scientific worldview, and in our usual pattern of school and work and peer pressure tends to stamp out mystical tendencies. (We're supposed to be on time, not daydream, focus on and believe what we can see and feel, etc.) I think prototype experiences and inclinations are probably there in each of us as young children in each of the various ways of looking at and experiencing the world. (For example, who hasn't had the experience of thinking about someone and then had them call on the phone, or found out that something unusual was going on for them at the time?) As adults, we can specifically nurture and train those ways of thinking and being and experiencing that may have been suppressed by our families or culture.
